VXLAN

VMware have just released a new design guide regarding Network Virtualisation. Particularly focusing around VXLAN….

http://blogs.vmware.com/vsphere/2013/03/download-vmware-network-virtualization-design-guide.html

As part of my new job, I’ve taken it upon myself to educate my peers on interesting articles released by VMware.

VXLAN is being mentioned quite a lot these days as VMware and Cisco start banging on about the move to a “Software-defined datacenter”. Up until last December, I was pretty must oblivious to virtual networking and have only recently started reading up on the stuff….. pretty tough going considering my poor understanding of network technologies! (One area I am striving to improve on).

So given what I’ve learnt, I thought it would be useful to briefly explain my understanding on VXLAN! =)

Virtual eXtensible LAN (VXLAN) basically expands on VMware’s network virtualisation by getting rid of the limitations of scale when implementing VLANs (4096), the problems of spanning a network across disparate data centres, and also the lack of multi-tenancy isolation – I believe you can get 16mil networks with VXLAN.

It’s designed to act as an L2 virtual network over the L3 physical network – in other words the L2 packet from the VM (MAC) is wrapped in a L3 IP header by the vSwitch and sent out over UDP. One of the advantages of this MAC-in-IP encapsulation is the ability to span a network domain across 2 different data centres – i guess similar to a stretched VLAN.

TBH, I can only envisage VXLAN being implemented in multi-tenancy cloud solutions to allow network scalability. However, it’s worth understanding the basics of VXLAN and what it is as I’ve seen customers catch hold of this “buzzword from VMware/Cisco” and think it’ll be useful to them. If I’m honest, if anyone asks about VXLAN then I would suggest you tell them that unless they’re going to break the limit of VLAN then don’t bother with it until the technology is fully matured – there are niggling issues with switch supportability (if it’s not a new cisco switch), routing issues caused by multiple IP addresses on the same subnet existing in multiple locations at the same time (think multi-tenancy cloud talking out via 1 internet gateway), etc. Probably more headaches than it’s worth…… not to mention a re-think of your network and the cost of implementing it!

 

Anyways, here are 2 great blogs that have helped me to understand VXLAN:

http://www.yellow-bricks.com/2012/11/02/vxlan-use-cases/

http://blog.scottlowe.org/2011/12/02/examining-vxlan/

(You can never go wrong with Duncan Epping and Scott Lowe!)

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